Understanding seed mortality and its effects on the Pacific Coast Shellfish Industry

The West Coast shellfish industry is an integral part of many coastal communities throughout the Pacific Northwest, and currently supports over 3000 family wage jobs across the region.  The farm gate value of shellfish sold each year exceeds $110 million, and contributes a total of $278 million per year in economic activity to rural communities along the coast.

Several consecutive years of dramatic seed shortages pose a serious threat to our industry, and to a way of life held by shellfish growers for over 130 years.  Many growers in the Northwest rely heavily on natural recruitment of oyster larvae, and after six years of failed natural sets in Willapa Bay, many growers are scrambling for solutions.


Production in some commercial hatcheries has also declined dramatically in recent years, leaving many established farmers short of product, and deeply concerned about the future of their industry. Whiskey Creek Shellfish Hatchery in Netarts, Oregon has been a consistent producer of oyster larvae for over thirty years, and typically supplies 75-80% of all growers in the Pacific Northwest.  Beginning in 2007, however, high larval mortality throughout the summer growing season reduced annual production to 25% of normal levels, and forced the hatchery to step back and identify the source of these unprecedented mortality events.

Research at the hatchery in recent years has identified the upwelling of acidified seawater as a major contributor to these larval mortality events.  The intrusion of corrosive seawater onto the Oregon continental shelf has been commonly observed in recent years (Feely et al 2008), and heavily influences the shallow waters of Netarts Bay.  Comparison of larval performance in the hatchery with environmental data in 2009 showed a strong relationship between the presence of upwelled, corrosive seawater and high mortality in young oyster larvae, which form their shells from aragonite.

The following graph summarizes production data collected June and July 2009, and correlates the survival and growth of oyster larvae with changes in seawater conditions.  During this period, winds reversed direction several times, producing alternating periods of upwelling and downwelling.  This pattern shows the dramatic effects of upwelled, acidified water on groups of young oyster larvae.


The strong correlation between high pCO2 and larval mortality has become an important diagnostic tool for the hatchery, and monitoring of seawater quality has allowed Whiskey Creek to ‘pick their moments’ and significantly increase hatchery production in both 2009 and 2010.  The success of these efforts underlines the importance of reliable, real-time data as a management tool for the Pacific Coast shellfish industry, and has fostered a number of collaborative efforts between the oceanographic community and shellfish growers throughout Oregon and Washington.  The outcome of these collaborations is a new network of monitoring stations established by PCSGA in areas of commercial importance, where real time data can be linked to larval performance, both in commercial hatcheries and in the natural environment.  NOAA funds help support this program, through the assistance of Senator Maria Cantwell.

The PCSGA monitoring program provides a stable platform for data acquisition at the exact locations of interest to our industry, including seawater intakes at commercial hatcheries and sites that traditionally support high natural recruitment of oyster larvae.  Larvae are present in commercial hatcheries from February-November each year, and these facilities provide the unique opportunity to examine trends in larval performance as ocean conditions evolve throughout the growing season.  These data will be used in concert with ongoing research projects throughout the Pacific Northwest, and together should provide valuable insights into the effects of seawater chemistry on shellfish larvae in the real ocean.  A number of exciting collaborations have already been established between PCSGA and the research community at large, which are outlined below.


Selected sites listed above will collect continuous pCO2 data in 2011, and both tCO2 and pCO2 will be monitored on site at Whiskey Creek in 2011.  In addition, all site participants will collect data in the following framework:

  • Continuous sampling of pH, temperature, salinity, and dissolved oxygen at all sites
  • Weekly Discrete samples at all sites – morning and afternoon samples at each site, analyzed for total carbonate chemistry, nutrients concentrations, DO, and bacteria levels
  • Detailed larval performance data from all sites to compare with environmental data


Pacific Coast Shellfish Grower’s Association (PCSGA)
120 State Ave. #142 Olympia, WA 98501